Helicopter antitorque propeller system



Feb. 11', 1947.

E. BOSS! HELICOPTER ANTI-TORQUE PROPELLER SYSTEM 2 Sheets-Sheet Filed Jan 18, 1944 llllnllllllllll l INi ENTOR.

ENE/I BOSS! Feb. 11, 1947.

HELICOPTER ANTI-TORQUE PROPELLER SYSTEM Filed Jan. 18, 1944 2 Sheets-Sheet 2 IN VEN TOR. ENEA BOSS HYY'OBNEY Patented Feb. 11, 1947 HELICOPTER TITGRQUE PROPELLER SYSTEM Enea Bossi, New York, N. Y. Application January 18, 1944, Serial No. 518,686

'2 Claims. (Cl. 2441'7) This invention relates to an anti-torque propeller system :for rotary wing aircraft. The conventional arrangement of an anti-torque propeller on the one side of the tail end of the fuselage of a rotary wing aircraft, such as a helicopter or autogyro, has anumberoi drawbacks. On the one hand, the Weight of the propeller supported in cantilever fashion creates a torque tending to twist the fuselage tail and thus is the cause of more or less severe vibrations. Furthermore, in many cases it is necessary to lengthen the tail beyond itsotherwise desired size in order to en sure that an anti-torque propeller or desired diameter does not interfere with the blades of the sustaining rotor of the craft.

The invention contemplates, therefore, the provision of an anti-torque propeller system Whereby the mentioned drawbacks may be eliminated or at least greatly reduced, and whereby certain advantages may be gained which cannot be obtained by the conventional device and arrangement. The invention consists in that an anti-torque propeller is provided on each side of the tail end of the fuselage so that the propellers rotate in opposite directions about a common axis transverse with respect to the fuselage. This arrangement balances torques caused by the weight of the propellers and renders it possible to do with propellers of smaller diameter than required if only one anti-torque propeller is used, so that in many instances the length of the fuselage tail may be also reduced. My invention further consists in that both propellers are of the variable pitch type so that their pitch may be controlled in flight, either together or independently of each other. The invention also consists in that one of such pair of independently controlled anti-torque propellers is subject to automatic pitch control under the action of a gyro whereas the pitch of the other propeller is operator-controlled.

Further details and objects of the invention will be apparent from the description given hereinafter and the accompanying drawings illustrating an embodiment thereof by way of example. In the drawings:

Fig. 1 is a diagrammatical top plan View of a rotary wing aircraft with an anti-torque propeller system according to my invention;

Fig. 2 is a side elevation thereof;

Fig. 3 is a top plan view of the tail end of the craft on a larger scale; and

Fig. 4 is a view similar to Fig. 1 and illustrating a modification of the control of the pitch variation.

Referring now to the drawings, the rotary wing I aircraft comprises the sustaining rotor I and the fuselage- 2 with its 'tail 3, carrying the anti-torque propeller system i. This system comprises the two propellers 5 and 6, respectively arranged on contains bevel gears i0 and I! secured to the stub axles l2 and I3 of the propellers 5 and 6 respectively, and meshing with the bevel drive wheel M. Wheel Hi is mounted on a drive shaft 15 which extends interiorly .of and-through the length 'of the tail 3 into the 'fuselage Z. The shaft !5 may be driven as well known in theart by any suitable powersource, e. g. by a motor (not shown) of the craft or by the sustaining rotor I as indicated in Fig. 1. In Fig. 3 the contours of two propeller blades l6 and I! in similar positions are entered in dash and dot lines. From a comparison of the two it will be clear that the propellers will rotate in opposite directions both with thrusts towards the right hand side of'the craft. The propellers are of the variable pitch type and may be of any suitable and conventional design. Variation of pitch can be accomplished by operating the control cable is for propeller 5 and control cable IQ for propeller 6, The cables are connected to chains 20 and 2| respectively, which cooperate with rotatable, teethed elements 22 and 23 of the pitch Varying mechanism interiorly of the propeller hubs.

The invention contemplates the possibilities of jointly varying the pitch of both propellers and of varying the pitch of the one propeller independently from that of the other. In order to cheat joint variation, both cables 18 and I9 may be operated, e. g. by means of a pedal 24 and-cable discs 25 and 25 mounted on the same axle 26. This is indicated in Fig. 4, where cable [8 runs on disc 25, and cable It on disc 25'.

In the event of independent variation of pitch, one of the cables may be operated by means of a pedal arrangement similar to that just described, but with only one disc 25 on axle 26, Whereas the other cable may be connected to any suitable and conventional control means. This is shown in Figs. 1 and 2 where according to my further invention, the mechanism for pitch variation of the one propeller is under the control of the pilot and the mechanism for pitch variation of the other propeller is automatically controlled by a gyro reacting on yawing movements of the fuselage. In the illustrated embodiment cable l8 associated with propeller 5 is attached to the disc 25 so that the pilot by using pedal 24 is enabled to vary the pitch of that propeller, The cable I9 of the other propeller 6 is connected to the non-rotatable but oscillatable part 21 of a gyro 28 which may be driven in conjunction with the rotor I so as to spin about a transverse axis 29. This arrangement will relieve the pilot of a considerable portion of the work necessary for the pitch control so that he will have to actuate the pedal 24 only if large alterations of the torque created by the anti-torque propeller system are required.

It will be clear to those skilled in the art that alterations and modifications of the structure shown may be made without departing from the spirit and essence of the invention, which shall be limited only by the scope of the appended claims.

, I claim:

1. In a rotary wing aircraft including a fuselage, an anti-torque propeller system comprising two variable pitch propellers, one on each side of the tail of the fuselage, said propellers having a common axis intersecting at right angles the plane of the longitudinal and vertical axes of the fuselage and being so arranged and constructed as to create thrusts both in the same direction, a common drive shaft for said propellers in the tail of said fuselage, means substantially in the end of said fuselage tail to transmit driving torques to said propellers in opposite directions,

two independent controls for varying the pitch of said propellers respectively, and means responsive 4 to yawing motions of the fuselage and in connection with one of said controls to actuate the latter.

2. In a rotary wing aircraft including a fuselage, an anti-torque propeller system comprising two variable pitch propellers, one on each side of the tail of the fuselage, said propellers having a common axis intersecting at right angles the plane of the longitudinal and vertical axes of the fuselage and being so arranged and constructed as to create thrusts both in the same direction, a common drive shaft for said propellers in the tail of said fuselage, means substantially in the end of said fuselage tail to transmit driving torques to said propellers in opposite directions, a control gyro, means in connection with said gyro and one of said propellers for varying its pitch under the action of said gyro, and operatorcontrolled means for varying the pitch of the other propeller.

ENEA BOSSI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,225,002 Focke Dec. 17, 1940 1,990,606 Junkers Feb. 12, 1935 1,806,648 Salisbury et a1 May 26, 1931 1,707,690 Sperry Apr, 2, 1929 1,635,897 Nelson July 12, 1927 1,890,931 Briner Dec. 13, 1932 

